【NEC】 NEAC-32 Magnetic Disk Unit

In 1965, NEC completed the NEAC-32 high-capacity magnetic disk memory unit for the FONTAC computer of the Japan Electronic Computer Technology Research Consortium.
This unit reduced access time by providing 16 movable heads, held at a fixed spacing, for each disk side. The magnetic heads used a flying system and had a float distance of 7μm. Since the system had multiple disks and magnetic heads, and used the flying system, it was difficult to synchronize using a timing track, and an FM modulation system was adopted to enable self-synchronization using information signals.

NEAC-32 Magnetic Disk Unit Specifications
Total memory capacity(bit) 270,336,000
Access time(msec) 30-80
Latency time(msec) Average 17
Disk dimensions(mm) 650ø×3
Number of disks(for data) 25
Number of recording sides(for data) 48
Number of tracks(per side) Inner zone 128+Outer zone 128
Track pitch(mm) 0.6
Number of magnetic heads(per side) Inner zone 8+Outer zone 8
Recording system FM
Recording density(bit/mm) Max. 17
Rotation speed(rpm AC60Hz) 1,800
Data transfer speed Inner zone 510kbit/s
Outer zone 770kbit/s
External dimensions(cm) 178(W)×100(D)×180(H)
Weight (kg) Approx. 1000
Power requirements 3KVA

NEAC-32 Magnetic Disk Unit